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July 13, 2012

Spintronic LED Invented

University of Utah physicists invented a new “spintronic” organic light-emitting diode or OLED that promises to be brighter, cheaper and more environmentally friendly than the kinds of LEDs now used in television and computer displays, lighting, traffic lights and numerous electronic devices.

“It’s a completely different technology,” says Z. Valy Vardeny.

The Utah physicists made a prototype of the new kind of LED – known technically as a spin-polarized organic LED or spin OLED – that produces an orange color. But Vardeny expects it will be possible within two years to use the new technology to produce red and blue as well, and he eventually expects to make white spin OLEDs.

However, it could be five years before the new LEDs hit the market because right now, they operate at temperatures no warmer than about minus 28 degrees Fahrenheit, and must be improved so they can run at room temperature, Vardeny adds.



A new “spintronic” organic light-emitting diode glows orangish (center) when the device, chilled well below freezing, is exposed to a magnetic field from the two poles of an electromagnet located on either side of the device. University of Utah physicists report inventing the new kind of LED in the July 13 issue of the journal Science. Photo Credit: Tho Nguyen, University of Utah.


Science - Spin-Polarized Light-Emitting Diode Based on an Organic Bipolar Spin Valve


The spin-polarized organic light-emitting diode (spin-OLED) has been a long-sought device within the field of organic spintronics. We designed, fabricated, and studied a spin-OLED with ferromagnetic electrodes that acts as a bipolar organic spin valve (OSV), based on a deuterated derivative of poly(phenylene-vinylene) with small hyperfine interaction. In the double-injection limit, the device shows ~1% spin valve magneto-electroluminescence (MEL) response, which follows the ferromagnetic electrode coercive fields and originates from the bipolar spin-polarized space charge–limited current. In stark contrast to the response properties of homopolar OSV devices, the MEL response in the double-injection device is practically independent of bias voltage, and its temperature dependence follows that of the ferromagnetic electrode magnetization. Our findings provide a pathway for organic displays controlled by external magnetic fields.

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